1. Field of the Invention
The present invention relates to a toroidal-type continuously variable transmission, and in particular, to a mechanism for advancing and retracting a power roller disposed between an input disk and an output disk in frictional contact therewith, in a plane orthogonal to the axis of rotation of both the disks.
2. Description of the Related Art
A prior art toroidal-type continuously variable transmission is disclosed, for example, in Japanese Patent Laid Open Publication Hei No. 7-91512. This continuously variable transmission is a full toroidal-type continuously variable transmission of the double cavity type including two sets of input and output disks. Each of the two sets of input and output disks includes an input disk, an output disk disposed on the same axis of rotation as that of the input disk, a power roller disposed in a toroid-like groove formed by opposing surfaces of both the input and output disks so that the power roller is in frictional contact with both the input and output disks, a carrier for rotatably supporting the power roller and for slanting a tilt and rotation axis of the power roller by a predetermined angle with respect of an axis line orthogonal to the axis of rotation of both the input and output disks, and a cylinder device for advancing and retracting the carrier in a plane orthogonal to the axis of rotation.
Furthermore, in this continuously variable transmission, an axis line of the cylinder device is slanted in the tilt and rotation axis direction so that an axis line of a carrier shaft mounted on the carrier along the tilt and rotation axis is aligned with the axis line of the cylinder device on a straight line, and the carrier shaft and a piston rod are coupled by a universal joint.
However, in the prior art toroidal-type continuously variable transmission, in order to dispose the cylinder device on the axis line of the carrier shaft, it was necessary to fix the cylinder device on a housing or the like in a condition in which the cylinder device is slanted with respect to an axis line which is orthogonal to the axis of rotation of the input and output disks. Then in the toroidal-type continuously variable transmission, since three power rollers are usually disposed about the axis of rotation at equal intervals in a toroid-like groove formed by a pair of input and output disks, when this continuously variable transmission is of the double cavity type, a total of six power rollers will be provided. As a result, according to the above-mentioned prior art technique, it was necessary to fix each of the six cylinder devices with the same slant angle to the housing or the like. In order to set each cylinder device accurately with that slant angle, it is required to improve the common working and the working accuracy of respective cylinder bodies and the housing or the like for securing the cylinder bodies. However, there is a drawback that the accurate mounting of the cylinder devices is not easy. Furthermore, since each cylinder device is slanted, there is another drawback that the layout of the cylinder devices and their peripheral equipment becomes complicated.